Heat exchanger



March 30, 1937. I c. E. LuckE HEAT EXCHANGER Filed May 26, 1951 4Sheets-Sheet l vF .R We T T. WA B March 30, 1937.

c. E. LUCKE 2,075,044

HEAT EXCHANGER Filed May 26, 1951 4 Sheets-Sheet 2 Fig 5 ATTORNEY Marci30, 1937. c. LUCKE HE-AT EXCHANGER Filed May 26, 1951 4 Sheets-Sheet s Wwm INVENTOR 6544/?! .63 5 406%5 ATTORNEY Patented Mar. 30, 1937 U ETEDSTATES PATENT Fr es The Babcock & Wilcox Company, Bayonne, N. 3., acorporation of New Jersey Application May 26, 1931, Serial No. 540,025

23 Claims.

This invention is concerned with fluid heat exchange apparatus.

In the operation of economizers difiiculties have been experienced'inregard to the irregularities of results. In one part of the apparatusthe contained fluid would be heated to the proper temperature, while inother partsthere would be such excessively high temperatures that steamwould be produced and collected. When this con-' dition has prevailed invarious parts of the apparatus, undesirable fluid actions have takenplace. These actions not only interferewith the economical operation ofthe steam generator fed by the economizer, but they are apt to bedestructive to the economizer structure. It is an object of thisinvention to overcome such difficulties.

More specifically, it is an object of the invention to provide foruniformity of operation of such fluid heat exchange apparatus as aneconomizer by causing all of the separate and contained fluid streams tobe afiected by all parts of the current of fluid acting upon thecontained stream.

A general object of the invention is to attain equalization of heatingin economizers which discharge separate streams of heated fluid. Theinvention provides for the uniformity of conditions of such separatestreams.

It is also an object of the invention to provide a fluid heat exchangeapparatus of the type mentioned with structures enabling the apparatusto be operated in accordance with difierent conditions of the current offluid operating upon the contained streams. For example, when there ismarked laning of the fluid current, the parts of the current at extremetemperatures may be eliminated from the operation. I

Further objects of the invention will appear as the accompanyingdescription proceeds.

The invention will be described with reference to the accompanyingdrawings in which:

Fig. 1 is a diagrammatic representation of a downflow economizerassociated with a steam boiler.

Fig. 2 is a diagrammatic view in the nature of a vertical sectionshowing an upflow economizer operating with a steam boiler.

Fig. 3 is an end view of the illustrative apparatus showing the casingend removed so as to expose the return bends of the economizer coils.

Fig. 4 is a diagrammatic view somewhat similar to Fig. 3 but disclosingparticularly the path of one of the contained streams of fluid in theapparatus.

Fig. 5 is an isometric view showing the coils for conducting theparticular contained fluid stream indicated in'Fig. 4.

Fig. 6 is a diagrammatic view in the nature of a vertical sectionthrough an economizer with fluid flow controls for controlling andlimiting the passage of the heating medium through an upflow economizer.

In the use of economizers the defect of unequalized heating may resultfrom one or both of two causes. The first of these causes relates tounequalized water flow across the entire flow of water through theeconomizer when the gas flow is uniform, the second cause relates to thenon-uniformity of gas flow as it contacts with the separate streams ofwater passing through the economizer. This non-uniformity may relate tomass flow or to the temperature of the fluid in movement, and theillustrative structures are designed to eliminate such defects.

Non-uniformity of gas flow in economizers is accentuated in largeinstallations and it is likely to attain its maximum when the gasvelocity is low. Under such conditions there may be such extremenon-uniformity that on one side of the gas flow chamber there is afalling gas current and on the other side there is a rising gas current.This is an extreme condition but is illustrative of conditions which arecorrected by the illustrative equipment.

In the type of economizer shown in the drawings, the uniformity ofdistribution of heating gases is best at high velocity.

Fig. 1 discloses an economizer having a water inlet header It at the topof a flue i 2. Water flows from the header l0 through flat coils I4arranged to zig-zag across the flue. At the bottom of the flue thesecoils discharge into an outlet header l6. As shown these flat, obliquelyarranged coils are connected together by horizontal pipes into a groupwhich connects the inlet and outlet headers. Each coil is formed ofstraight sections of pipe connected by return bends to form zigzag flatcoils.

Feed water enters the header l0 through an inlet l8 and is preferablyforced through the economizer under pressure. After proceeding throughthe coils it flows through the outlet connection 20 to the steam andwater drum 22 of the associated boiler construction.

Figs. 4 and 5 indicate a coil construction and arrangement of tubes forconducting the contained stream of water through and across the current.of furnace gases moving upwardly through the flue I 2 Each coil consistsof a series of straight tube sections connected by return bends. Asindicated, the inlet header All is formed with a row of ports or tubeseats some of which are indicated at .25, 2t and 2c. The upper coil Mleads from the tube seat 26 and extends obliquely across the flue to aposition indicated at iii. A similar but shorter coil will be understoodto lead from the tube seat 2 3 to a position at one side of the flue.From that point its contained fluid stream flows preierably horizontallyacross the hue to a position indicated at $6, whence it proceeds throughanother fluid coil to the position indicated at Starting from the tubeseat a much shorter fluid coil leads obliquely to a point at one side ofthe economizer indicated at From that point its'contained fluid streampasses through a horizontal pipe to the right where it enters the upperend of another coil and then flows in zigzag manner back and iorthacross the flue similarly to the movement of the contained streams inthe other coils.

Successive sections of the fluid coils conduct the water across the flueat successively different levels. Each section is also located in adifferent vertical part of the stream to the end that each stream ofcontained fluid flows through every cross-sectional part of the gasstream. The location of corresponding tubes of adjacent coils in offsetrelationship further promotes equalization of the heat transfer to thecontained fluid.

In the structure indicated in Fig. l, furnace gases flow upward throughthe flue l2 and out the stack The gases proceed into the lower part or"the flue from the last pass Mi of the boiler section The apparatusindicated in Fig. 2 includes a boiler section it into which the furnacegases proceed as indicated by the arrows 563 and 52. From the last gaspass 56 the furnace gases pass into the inlet 56 of the economizer flue58. They are discharged from the bottom of the economizer through theconduit til. In this modification also, the contained streams of fluidto be heated pass in a direction the reverse of the direction of themovement of the furnace gas. The fluid passes from the inlet headerthrough groups of zigzag coils to the outlet header t l.

Fig. 3 indicates the arrangement of return bends at the ends'cf theindependent. tubes in the economlzer. The zig-zag path of one stream offluid is indicated by arrows extending from the inlet header to theoutlet header. Each separate stream of fluid moves through a similarpath.

In considering-the operation of the structures shown in Figs. 4 and 5 itis to be noted that aninequality of heating conditions across theapparatus is corrected. Thus, unequal gas flow or variant temperatureconditions do not interfere with equalized heating.

In Fig. 6 there is shown a counter-flow econ,- omizer in which the flowof the heating medium is controllable as to volume and cross-section atthe will of the attendant; The flue B6 is divided by partitions 68extending from the gas inlet 10 to the gas outlet 12. Separated gaspassages 14, 15, I6 and 11 are thus provided.

- At the inlet end of the separated gas passages dampers 18 are located.The independent operation of these dampers permits the control of heattransfer in one or more of the passages I4, 15, 16 and I1 as theconditions. of operation demand. The flow of the heating medium may bethereby controlled so as to correspond to the aovaoee load conditionsunder which the system is op crating. The laning of the heating gases inthe economizer may be thus counteracted. if, for example, with all ofthe dampers in open position, the gases flowing through the passage "a lare of exceedingly high temperature, that passage may be closed and thegases divided among the remaining passages.

Selective distribution of the fluid to be heated renders theillustrative apparatus more adaptable to the dififerent operatingconditions to be met. The provision of separate inlet headers so, 82,

and 88 permits of such distribution. Preferably these headers haveseparate connections 88, 9d, Q2 and connecting with the fluid inlet 96.Selective flow of the fluid from the inlet 96 to the separate headersdepends upon the conditions of the valves t8, it being understood thatthere is a separate valve for each of the connections 88, til, 5'2 and9M.

Different temperature and flow conditions in the economizer arecontrolled by suitable setting of the various fluid control devicesabove described. Thus, by appropriate setting of these devices suchactions as water hammer and actions causing a steam bound condition maybe prevented. Extreme flexibility and adaptability of operation of theeconomizer is thus provided.

Arrangement of the tubes in passages it, and ii in such a zig-zag manneras indicated in Figs. 2, 4. and 5 further promotes uniformity of resultsand increases the effectiveness of the illustrative apparatus.

The device illustrated in Fig. 6 of the drawings is capable of producinga gas velocity which is independent of any one of the following:

1. Boiler load.

2. Velocity of the gas on entry to the economizer casing.

3. Velocity of the gas leaving the economizer casing.

4. Total weight of the gas passing through the economizer.

ihe structurev illustrated in Fig. 6 includes the boiler tilt associatedwith a furnace H02. Above the furnace is a water tube boiler section N24with a superposed steam and water drum Hi6.

While this invention has been described with reference to the particularstructures shown in "the drawings, it is to be understood that it is notlimited thereto, but is of a scope commensurate with the scope or" thesub-joined claims.

What is claimed is:

1. An economizer comprising, in combination,

walls forming a passage for the flow of a stream of heating gases, aninlet header extending transversely of the passage, a similarlypositioned outlet header, and return bend coils of tubin formed ofaligned sections extending back and forth across the passage so thatevery cross-sectional part of the stream of heating medium contacts witha coil section, said coils conducting water from the inlet header to theoutlet header with a flow which is counter-current with respect to theflow of heating gases.

2. An economizer comprising, in combination, a casing defining a passagefor the flow of heating gases, a water inlet header arrangedtransversely of the casing, groups of successive tubes displacedvertically and horizontally with reaovaosa 3 to an economizer; theeconomizer comprising, a.

water inlet chamber, an outlet chamber, a heating gas flue constructionhousing groups of return bend water conducting tubes each transmittingwater in a separate and independent stream from the inlet chamberthrough the flue construction to the outlet chamber with the tubes ofeach group arranged in zig-zag formation and each group containing aplurality of coils, and means for conducting heating gases to the flueconstruction so that they pass therethrough in ,a directioncounter-current to the flow of water.

4. An economizer comprising, in combination, a casing constituting aflue for the passage of heating gases, a water outlet header extendingtransversely of the flue, tubes for conducting water in separatedstreams through the flue to the outlet header, partitions extendingthrough the flue and between the tubes to divide the flue into aplurality of separated gas passages, means at the end of each of saidpassages for controlling and preventing the movement of'heating gasesthrough the passage, a separate water a inlet header for each passage,9, feed water inlet main, separate conduits leading from said main tothe separate inlet headers, and separate valves for selectivelyestablishing communication between said main and said conduits.

'5. An economizer comprising, in combination, a casing forming a fluefor the passage of a heating gas therethrough, tubes conducting waterthrough the flue, means for forming a plurality of longitudinal zones inthe flue, means for varying the volume of heating gases passing througheach of said zones, and means for controlling the inflow of water tosaid zones, so that the flow to one zone can be varied independently ofthe flow to any of the other zones. I

6. Fluid heat exchange apparatus comprising, in combination, a casinghaving partitions forming a plurality of parallel passages for the flowof a heating medium, means for conducting a separate group of containedfluid streams in a zigzag path through each passage, separated means forsupplying fluid to the separate groups, and means for regulating theflow of heating medium through any passage independently of the flowconditions in the other passages.

7. In an economizer; walls forming a passage for the flow of a stream ofheating gases, a row of water inlets extending transversely of thepassage, a similarly positioned row of outlets, groups of spaced returnbend coils of tubing connected in series with each coil formed ofaligned sections and the sections of each coil extending back and forthacross the passage so that every cross-sectional part of the stream ofheating medium contacts with the tubes of the individual groups, andmeans for. connecting each group to an inlet and an outlet, said groupsconducting water. from the inlets to the outlets with a flow which iscounter-current with respect to the flow of heating gases.

8. In an economizer, a flue constituting a gas and water conductingconduit coils proceeding obliquely of the gas pass flue from positionsspaced transversely of the flue to compensate for non-uniform gasdistribution or velocity in the flue and to provide for uniform heatingof the fluid passing through the various coils.

9. In fluid heat exchange apparatus, a flue longitudinally of which aheating fluid flows in a single pass, means for conducting a fluid to beheated through the flue in parallel flow circuits of equal lengthsbetween inlets and outlets, each circuit comprising serially connectedflat coils of return bend tubes arranged obliquely to the longitudinalaxis of the flue, the first coil of each circuit being of a lengthdiiferent from the lengths of the first coils of adjacent circuits.

10. In fluid heat exchange apparatus, walls forming a passage directinga heating fluid, and groups of tubes connected in series to conductcontained streams of a heat absorbing fluid through the passage inparallel and independent flow circuits, said groups of connected tubesincluding some which conduct their confined fluid streams back and forthtransversely of the passage toward and from spaced pairs of oppositewall portions.

11. In an economizer, a flue for the passage of furnace gases, tubesconveying separate streams of fluid through the flue, and tubeconnections whereby each stream of contained fluid flows recurrently andobliquely entirely across the flue and simultaneously generally in adirection counter to the flow of furnace gases.

12. In fluid heat exchange apparatus, a flue for the passage of heatinggases, tubes providing for the flow of a plurality of independentstreams of fluid through the flue and transversely of the heating gases,and connections between the tubes forming independent fluid flowcircuits, individual and successive tubes in the independent flowcircuits being displaced longitudinally of the gas flow and transverselyof the flue whereby the flow of each circuit is subjected to the heat ofthe gas in every cross-sectional flow area of the flue.

13. In an economizer, a flue, means providing for a flow of heatinggases through the flue, tubes providing for the flow of a plurality ofindependent streams of fluid through the heating gases in the flue, andmeans for connecting the tubes to cause said streams to flow back andforth transversely oi the flue and between two opposite sides of theflue and to cause said streams to simultaneously flow recurrentlytransversely of the flue between two other opposite sides of the flue.

14. In an economizer, a flue for the passage of furnace gases, tubesconveying separate streams of fluid through the flue, and tubeconnections whereby each stream of contained fluid flows rei currentlyobliquely entirely across the flue and in a direction counter to theflow oi i'urnace gases.

15. In apparatus of the type wherein an economizer and boiler areconnected for fluid flow,

water through the flue in separate streams, means connecting the tubesso that they form successive flat coils of return bend. sectionsextending obliquely to the longitudinal flow axis of the flue, and a gasflow restrictor for varying the velocity of the gases through the flueindependently of the velocity of the gases as they pass to the inlet ofthe flue.

1'7. In fluid heat exchange apparatus, a flue, means providing aplurality of passages in the flue for separate streams of heating mediumin longitudinal zones in the flue, means for conducting separate andindependent streams of fluid across the flue so that each stream crossesevery crosssectional part of a stream of heating medium, and

means for selectively diminishing at will the flow of heating mediumthrough separate longitudinal zones of the flue.

18. In an economizer, an inlet chamber for heating gases; an outletchamber for said gases; walls forming a large main gas flue connectingsaid chambers; a row of inlets at one end of the flue for a fluid to beheated; a row of fluid outlets at the other end of the flue; tubesconnecting opposite inlets and outlets to provide separate fluid flowpaths through the flue; and means for compensating for the nonuniformityof heating throughout the flue; said last named means comprising wallsdividing said flue longitudinally into a plurality of separate andparallel heating gas passages, and independently operable meansregulating the flow of heating gases through the passages, there beingseparate fluid flow paths for the separate passages through which flowin the same direction contained streams of a fluid to be heated.

19. In heating gases; an outlet chamber for said gases; walls forming alarge main gas flue connecting 3 said chambers; a row of inlets at oneend of the flue for a fluid to be heated; a row of fluid outlets at theother end of the flue; tubes connecting opposite inlets and outlets toprovide separate fluid flow paths through the flue; and means 40 forcompensating for the non-uniformity of heating throughout the flue; saidlast named means comprising walls dividing said flue longitudinally intoa plurality of separate and parallel heating gas passages, independentlyoperable means regulating the flow of heating gases through thepassages, and separate fluid inlet headers corresponding in number tothe number of said passages, there being separate fluid flow paths forthe separate passages through which flow in the same direction containedstreams of a fluid to be heated.

an economizer, an inlet chamber for 20. In an auxiliary fluid heaterarranged to receive waste heating gases from an associated steam boiler,fluid heating surface arranged to receive the heating gases in heattransfer contact therewith, and means for varying the amount of saidheating surface contacted by said heating gases while maintaining all ofthe heating gases received by said fluid heater in heat transfer contactwith at least a portion of said heating surface, whereby heatingconditions in said fluid heater are controllable and corrosion of saidheating surface may be minimized.

21. In an economizer arranged to receive waste heating gases from anassociated steam boiler, water heating surface arranged to receive theheating gases in heat transfer contact therewith, and means for varyingthe amounts of heating gases contacting with different portions of saidheating surface while maintaining all of the heating gases received bysaid fluid heater in heat transfer contact with at least a portion ofsaid heating surface, whereby heating conditions in said economizer arecontrollable and corrosion of said heating surface may be minimized.

22. In an auxiliary fluid heater arranged to receive waste heating gasesfrom an associated steam boiler, fluid heating surface divided intoaplurality of separate flow sections arranged to receive'the heatinggases in heat transfer contact therewith, and means for varying theamounts of heating gases contacting with different sections of saidheating surface while maintaining all of the heating gases received bysaid fluid heater in'heat transfer contact with at least one section ofsaid heating surface, whereby heating conditions in said fluid heaterare controllable and corrosion of said heating surface may be minimized.

Y 23. In an auxiliary fluid heater arranged to receive waste heatinggases from an'associated steam boiler, a casing arranged to receive theheating gases, wall means dividing said casing into a pluralityofseparate-parallel flow heating gas passes, a fluid heating surfacesection arranged in each of said gas passes, and means for varying thenumber of said gas passes having a' heating gas flow therethrough,whereby heating conditions in said fluidheater are controllable andcorrosion of said heating surface may be minimized.

' CHARLES E. LUCKE.

